High CPU Load After Update to v4.3

I run a busy high traffic and high community participation site, so MySQL has always run very high on my server. But after upgrading to v4.3 (no other change), my CPU load tripled, and it’s crippling the server, causing frequent crashes and generally degraded responsiveness.

The site is hosted on a high end dedicated server with 4 SSD drive in hardware RAID. I spoke with my host and they assured me no changes have been done to the server, and all server side applications are up to date.

Problems started after the update to v4.3, No other change whatsoever has been done to neither the WP installation, nor the server itself.

My log shows high http connection count, which use abnormally high CPU never seen before:

I’m on a reliable dedicated server, as I had mentioned earlier. One other person who commented here is also on a dedi.

I also use CloudFlare Pro, and contacted their tech to verify and make sure the traffic is still properly filtered through their CDN and content is served from their caches. There’s no change there.

Perhaps it would be a different matter if didn’t so obviously start after update to v4.3 with no other change done to the set up. This has also never happened before, so it’s not an old problem coming back.

I’m having the same problem where I can’t even get to my Dashboard Admin pages unless I keep monkeying around disabling plugins to get the Admin side to work. The client facing side is okay as CloudFlare is dishing out the pages from their cache.

Currently I can’t get into my Dashboard.

Hopefully a 4.3.1 update can get pushed out to resolve these problems.